1. Field of the Invention
The present invention relates to a technique for managing files in a telephone switching system, and more specifically, to a technique for managing files of the telephone switching system using a flash memory as a storage medium.
2. Description of the Related Art
Generally, a private branch exchange (PBX) or keyphone system, referred to hereafter as a switching system, includes a central processing unit (CPU) which controls the overall operations of the system including the controlling of switching of talking and providing various services for subscribers. A read only memory stores programs of the CPU and initial service data, for performing fundamental calling and various functions. A random access memory temporarily stores data processed by the CPU. A switching circuit switches various tones and voice data under the control of the CPU. A general subscriber circuit supplies talk current to general telephones and at the same time interfaces signals between the switching circuit and the general telephones under the control of the CPU. A ring generator generates a ring signal and supplies it to a subscriber line. A keyphone subscriber circuit transmits and receives various data to and from keyphones, supplies talk current, and interfaces signals between the keyphones and the switching circuit under the control of the CPU. The keyphones and the general telephones are extension subscribers and the line connecting the general subscriber circuit and the keyphone subscriber circuit to the extension subscribers is the subscriber line.
A tone generator generates various tone signals and supplies them to switching circuit under the control of the CPU. An office line circuit seizes office lines to form an office line speech loop and interfaces signals between the office line and the switching circuit under the control of the CPU. The office line is the line connecting the office circuit to an exchange. The DTMF (dual tone multifrequency) receiver analyzes a DTMF signal supplied from the switching circuit and converting it into digital data and supplies the digital data to the CPU. The DTMF signal received by the DTMF receiver may be a telephone number generated by an extension subscriber through an office line or a telephone number generated by an external subscriber. A DTMF transmitter converts the digital data output from the CPU into a DTMF signal and supplies it to the switching circuit.
The switching circuit described above includes a read only memory for storing the program and initial service data and the random access memory for temporarily storing data processed by the CPU. However, these memories do not have sufficient capacity for storing and managing the entire program and database required in a large-capacity switching system. Accordingly, the switching system uses a hard disk drive as a large-capacity storage medium.
The hard disk drive is connected to the CPU through an input/output controller. The hard disk drive stores the program and database of the switching system and the program and database are controlled and managed by the CPU.
The hard disk needs a separate controller for controlling the interface between the hard disks due to its characteristics. This hard disk control interface is frequently modified because the hard disk is often changed according to its rapid development in computer technology. Furthermore, a fairly large space must be secured for installing the hard disk.
The following patents each disclose features in common with the present invention but do not teach or suggest the specifically recited technique for managing the files of a switching system utilizing a flash memory instead of a hard disk drive: U.S. Pat. No. 5,465,292 to Takahashi et al, entitled Trading Telephone, U.S. Pat. No. 5,471,523 to Smith et al., entitled Telephone Call And Voice Processing System, U.S. Pat. No. 5,640,448 to Toyoshima, entitled Key Telephone System Capable Of Simulation By Button Operations, U.S. Pat. No. 5,251,254 to Tanigawa et al., entitled Control Of Incoming And Outgoing Calls In A Key System, U.S. Pat. No. 5,144,653 to Masuoka, entitled Telephone System Capable Of Automatically Distributing Terminating Calls And Method Of Performing Communication Within The Telephone System, U.S. Pat. No. 4,763,354 to Fukushima et al, entitled Key Telephone System, U.S. Pat. No. 4,782,514 to Oshikata et al., entitled Key Telephone System, U.S. Pat. No. 4,506,346 to Bennett et al, entitled Programmable Cartridge Telephone Communication System, U.S. Pat. No. 4,821,316 to Okumura et al, entitled Key Telephone System, U.S. Pat. No. 4,595,800 to Nagatomi et al., entitled Key, Telephone System, U.S. Pat. No. 4,602,132 to Nagatomi et al., entitled Key Telephone System, U.S. Pat. No. 4,703,416 to Crupi et al., entitled Apparatus For Locating Programs Resident On A Cartridge Of A Cartridge Programmable Communication System, and U.S. Pat. No. 5,583,856 to Weir, entitled Integrated Network Switch With Large Capacitor Switch Architecture Using Selectable Interfaces Between Peripherals And Switch Memories.